Calcining magnesium carbonate or hydroxide at 1,500–2,000 °C yields unreactive 'dead-burned' magnesia, whose 2,852 °C melting point makes steelmaking refractories its largest global consumer.
Compacted MgO powder insulates tubular electric stove heating elements and mineral-insulated copper-clad fire-survival cables because it conducts heat while blocking current.
Crystalline MgO thin films serve as tunnel barriers in magnetic tunnel junctions, achieving room-temperature tunnel magnetoresistance up to 600% compared with roughly 70% for amorphous alumina.